几道解不等式 1.X²-2X-3>0 2.X²+3X-4≤0 3.3X²-7X+2<0 4.-X²-X+20>0

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几道解不等式 1.X²-2X-3>0 2.X²+3X-4≤0 3.3X²-7X+2<0 4.-X²-X+20>0
几道解不等式 1.X²-2X-3>0 2.X²+3X-4≤0 3.3X²-7X+2<0 4.-X²-X+20>0

几道解不等式 1.X²-2X-3>0 2.X²+3X-4≤0 3.3X²-7X+2<0 4.-X²-X+20>0
1.X²-2X-3>0
(x-3)(x+1)>0
x>3 or x